Material handling equipment, such as lift trucks and the like, employ elevating mechanism for lifting and moving loads. In a common configuration for lift trucks, a pair of forks are slid under a load, and then raised to lift the load.
The load can then be moved and placed in another location, or stacked on other articles.
Since loads are not always piled evenly, surfaces are irregular, and articles themselves can be of different shapes, it is often necessary to tilt the forks forward or backward and from side to side to evenly engage the load, or to disengage from the load. Lift trucks are designed with this capability. Thus, the operator has many individual functions to perform in addition to starting, stopping, speed control and steering. The operator must raise and lower the forks and tilt them forward, backward, left or right. In large warehousing and product transfer facilities, operator efficiency can impact significantly the overall product movement rates. Efficient lift truck operators raise, lower and tilt the forks even as the lift truck is moving. To do so efficiently and safely, controls must be conveniently located, to require minimal arm movement to adjust from one control to another.
It is known to use joystick type switches for movement control of many devices. Known joystick switches are mechanical devices. Advantageously, joystick switches can be used to combine multiple functions in a single control, and if mounted on a handle or grip can be activated by a single finger or thumb.
Thus, a joystick module can be used advantageously in a lift truck control to tilt the forks or perform other control functions.
However, known mechanical joystick modules are inconveniently large, thereby reducing the number of controls for other functions that can be included conveniently in a single grip, for example. Further, warehousing and product handling environments can be extreme. For example, lift trucks are used in refrigerated facilities, and may move continuously and repetitively between warm and cold air areas. Lift trucks often are used outdoors and subjected to weather extremes. Further, lift trucks also are used in dirty, dusty environments.
Mechanical joysticks switches can fail if subjected to such extreme conditions for a prolonged period of time. As a result of the mechanical mechanism therein, known joystick modules which have anticipated lifetimes that are inconveniently short, requiring periodic replacement throughout the life of a fork lift truck.
What is needed is a compact joystick module that can withstand temperature extremes and fluctuations and continue to operate in dirty conditions for a prolonged, extended period of time.